crypto-miller-rabin/dist/index.js

Implementation of the Miller-Rabin primality test.

/* IMPORT */
import getRandomInRange from 'crypto-random-in-range';
import fme from 'fast-mod-exp';
import { PRIMES_1000 } from './constants.js';
/* MAIN */
//URL: https://en.wikipedia.org/wiki/Miller%E2%80%93Rabin_primality_test
const isProbablyPrime = (n, k = 8) => {
    /* FAST EXACT CHECKS */
    if (n <= 1n)
        return false;
    for (let i = 0, l = PRIMES_1000.length; i < l; i++) {
        const prime = PRIMES_1000[i];
        if (n % prime === 0n)
            return n === prime;
    }
    if (n <= 1000n)
        return false;
    /* PROBABILITISTIC CHECKS */
    let s = 0n;
    let d = (n - 1n);
    while ((d & 1n) === 0n) {
        s += 1n;
        d >>= 1n;
    }
    for (let i = 0; i < k; i++) {
        const a = getRandomInRange(2n, n - 2n);
        let x = fme(a, d, n);
        let y = 0n;
        for (let j = 0; j < s; j++) {
            y = fme(x, 2n, n);
            if (y === 1n && x !== 1n && x !== (n - 1n))
                return false;
            x = y;
        }
        if (y !== 1n)
            return false;
    }
    return true;
};
/* EXPORT */
export default isProbablyPrime;